French Foreign MinisterAlain Juppé said EU nations no longer believe Iran’s assertion that its program is for civilian use, and said that sanctions are an alternative to military action.

According to OPEC figures, the EU took 890,000 barrels per day from Iran in 2010. Making up for this shortfall will be a challenge. Currently, Saudi Arabia produces roughly 10 million barrels per day, but says its maximum capacity is 12.5 million barrels.

“Whether they can reach this figure is unclear,” says Mr. Stevens, author of a recent Chatham House study, “An Embargo on Iranian Crude Oil Exports: How Likely and with What Impact?”

The sanctions mean no new contracts will be signed with Iran, and that existing contracts must cease by July 1. Yet with a May 1 review to examine the effect of sanctions on EU economies, particularly beleaguered Greece, which takes 30 percent of its oil from Iran, there is what Stevens terms “wiggle room.”